Hydroxymethyl Furfural Oxidation Methods

ABSTRACT

A method of oxidizing hydroxymethylfurfural (HMF) includes providing a starting material which includes HMF in a solvent comprising water into a reactor. At least one of air and O 2  is provided into the reactor. The starting material is contacted with the catalyst comprising Pt on a support material where the contacting is conducted at a reactor temperature of from about 50° C. to about 200° C. A method of producing an oxidation catalyst where ZrO 2  is provided and is calcined. The ZrO 2  is mixed with platinum (II) acetylacetonate to form a mixture. The mixture is subjected to rotary evaporation to form a product. The product is calcined and reduced under hydrogen to form an activated product. The activated product is passivated under a flow of 2% O 2 .

RELATED PATENT DATA

This patent resulted from a divisional of U.S. patent application Ser.No. 11/932,436 which was filed on Oct. 31, 2007 which claims priorityunder 35 U.S.C. §119 to U.S. Provisional Application No. 60/863,704,which was filed Oct. 31, 2006.

TECHNICAL FIELD

The invention pertains to hydroxymethylfurfural oxidation methods,methods of producing diformyl furan and methods of producing anoxidation catalyst.

BACKGROUND OF THE INVENTION

Hydroxymethylfurfural (HMF) is a compound which can be produced fromvarious hexoses or hexose-comprising materials. HMF can in turn beconverted into a variety of derivatives, many of which are currently orare quickly becoming commercially valuable. Oxidation of HMF can produceoxidation products including diformyl furan (DFF), hydroxymethyl furancarboxylic acid (HMFCA), formylfuran carboxylic acid (FFCA), andfurandicarboxylic acid (FDCA). Uses for these oxidation products includebut are not limited to adhesives, sealants, composites, coatings,binders, foams, curatives, monomers and resins.

Although numerous routes and reactions have been utilized for preparingone or more of the oxidation products set forth above, conventionalmethodology typically results in low HMF conversion, low productselectivity and/or low product yield. It is desirable to developalternative methodologies for oxidation of HMF and production of HMFoxidation products.

SUMMARY OF THE INVENTION

In one aspect the invention pertains to a method of oxidizinghydroxymethylfurfural (HMF). The method includes providing a startingmaterial which includes HMF in a solvent comprising water into areactor. At least one of air and O₂ is provided into the reactor. Thestarting material is contacted with the catalyst comprising Pt on asupport material where the contacting is conducted at a reactortemperature of from about 50° C. to about 200° C.

In one aspect the invention pertains to a method of producingdiformylfuran. The method includes providing a mixture comprising HMFand an organic solvent. The mixture is contacted with a catalystcomprising active γ-MnO₂. The mixture is subjected to reflux temperaturefor a time of from about 6 hours to about 12 hours.

In one aspect the invention includes a method of producing an oxidationcatalyst. ZrO₂ is provided and is calcined. The ZrO₂ is mixed withplatinum (II) acetylacetonate to form a mixture. The mixture issubjected to rotary evaporation to form a product. The product iscalcined and reduced under hydrogen to form an activated product. Theactivated product is passivated under a flow of 2% O₂.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 shows conversion of HMF and selective production of furandicarboxylic acid and formylfuran carboxylic acid as a function of timeon stream utilizing a continuous flow reactor with a 5% platinumsupported on carbon catalyst and a base set of parameters in accordancewith one aspect of the invention. The parameters included P=150 psig,T=100° C., 0.828% Na₂CO₃ added to 1% HMF, liquid hourly space velocity(LHSV)=7.5-15 h⁻¹, air gas hourly space velocity (GHSV)=300 h⁻¹,catalyst reduced at 30° C. wet.

FIG. 2 shows HMF conversion and product selectivity as a function oftime on stream using the catalyst of FIG. 1 at a decreased temperature(T=70° C.), LHSV=4.5-7.5 h⁻¹ and air GHSV=300-600 h⁻¹ (all otherparameters and conditions being as set forth above with respect to FIG.1).

FIG. 3 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 and the parameters asset forth for FIG. 2 except for temperature (T=50° C.).

FIG. 4 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 and the conditions asset forth at FIG. 2 with the exception of the temperature which wasT=30° C.

FIG. 5 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 and the conditions ofFIG. 2 with a decreased concentration of Na₂CO₃ of 0.414% and T=100° C.

FIG. 6 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 and the conditions ofFIG. 1 except with an increased Na₂CO₃ concentration of 1.66%.

FIG. 7 shows HMF conversion and product selectivity as a function oftemperature using the catalyst of FIG. 1. P=150 psig, 0.828% Na₂CO₃added to 1% HMF, LHSV=7.5 h⁻¹ air, GHSV=300 h⁻¹, data taken at time onstream=140 min.

FIG. 8 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 at the specifiedtemperature and GHSV (either air or O₂). P=150 psig, T=100-115° C.,2.486% Na₂CO₃ added to 3% HMF LHSV=4.5 h⁻¹, air GHSV=300-600 h⁻¹ or O₂GHSV=600 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 9 shows HMF conversion and product selectivity as a function oftime on steam utilizing the catalyst of FIG. 1 under air or O₂ at variedLHSV and/or GHSV. P=150 psig, T=130° C., 0.828% Na₂CO₃ added to 1% HMF,LHSV=7.5-15 h⁻¹, air GHSV=300-600 h⁻¹ or O₂ GHSV=600 h⁻¹, catalystreduced at 30° C. wet.

FIG. 10 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 at P=150 psig air,T=100° C., 1% HMF, LHSV=7.5-15 h⁻¹, GHSV=300 h⁻¹.

FIG. 11 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 1 and the conditions ofFIG. 10 with the exception of 0.8% added Na₂CO₃.

FIG. 12 shows conversion of HMF and selective production of theindicated products as a function of time on stream utilizing acontinuous flow reactor with a 5% Pt supported on SiO₂ catalyst and abase set of parameters in accordance with one aspect of the invention;1% HMF, 150 psig air, 60-100° C., LHSV=13-19.6 h⁻¹, GHSV=261 h⁻¹.

FIG. 13 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 12 in the presence of 0.8%Na₂CO₃. (1% HMF, 0.8% Na₂CO₃, 150 psig air, 100° C., LHSV=13-6.5 h⁻¹,GHSV=261 h⁻¹.)

FIG. 14 shows HMF conversion and product selectivity utilizing a 9.65%Pt supported on carbon catalyst. The conditions utilized were P=150psig, T=100° C., 0.828% Na₂CO₃ added to 1% HMF LHSV=7.5-15 h⁻¹, airGHSV=300 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 15 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 14. P=150 psig, T=100° C.,2.414% Na₂CO₃ added to 3% HMF LHSV=4.5 h⁻¹, air GHSV=600 h⁻¹, catalystreduced at 30° C. wet.

FIG. 16 shows HMF conversion and product selectivity as a function oftime on stream for various air GHSV and LHSV. P=150 psig, T=100° C., 1%HMF LHSV=7.5-15 h¹, air GHSV=75-300 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 17 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 14 at varied temperatureand LHSV. P=150 psig, T=60-100° C., 1% HMF LHSV=3-7.5 h¹, 1% O₂ dilutedair GHSV=300 h¹, catalyst reduced at 30° C. wet.

FIG. 18 shows HMF conversion and selective product production utilizinga 5% Pt on an Al₂O₃ support catalyst as a function on time on stream atvaried LHSV. P=150 psig, T=100° C., 1% HMF LHSV=15-7.5 h⁻¹, air GHSV=300h⁻¹, catalyst reduced at 30° C. wet.

FIG. 19 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst FIG. 18 at an increasedtemperature (130° C.) relative to FIG. 18. P=150 psig, 1% HMF LHSV=7.5h⁻¹, air GHSV=300 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 20 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 in the presence of O₂.P=150 psig, T=100° C., 1% HMF LHSV=7.5 h⁻¹, 100% O₂ GHSV=300 h⁻¹,catalyst reduced at 30° C. wet.

FIG. 21 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 and the conditions ofFIG. 20 with the exception that P=300 psig.

FIG. 22 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 and the conditions ofFIG. 20 with the exception that 100% O₂ GHSV=600 h⁻¹.

FIG. 23 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 at varied LHSV. P=150psig, T=100° C., 1% HMF LHSV=7.5-4.5 h⁻¹, air GHSV=600 h⁻¹, catalystreduced at 30° C. wet.

FIG. 24 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 at varied LHSV in thepresence of O₂. P=150 psig, T=100° C., 0.828 weight % Na₂CO₃ added to 1%HMF LHSV=7.5-4.5 h⁻¹, O₂ GHSV=300 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 25 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 at varied LHSV andGHSV. P=150 psig, T=100° C., 0.828% Na₂CO₃ added to 1% HMF LHSV=4.5-7.5h⁻¹, air GHSV=300-600 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 26 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 at varied LHSV andGHSV. P=150 psig, T=70° C., 0.828% Na₂CO₃ added to 1% HMF LHSV=4.5-7.5h⁻¹, air GHSV=300-600 h⁻¹, catalyst reduced at 30° C. wet.

FIG. 27 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 18 in an 8 mL catalyst bedin the presence of air and then O₂. P=150 psig, T=100° C., 0.5% HMFLSHV=3.75 h⁻¹, air then O₂ GHSV=150-263 h⁻¹, catalyst reduced at 30° C.wet.

FIG. 28 shows HMF conversion and selective product production as afunction of time on stream utilizing a 5% Pt on a ZrO₂ support catalystat varied LHSV in a continuous flow reactor. P=150 psig air, T=100° C.0.5% HMF LHSV=7.5-3 h⁻¹, GHSV=300 h⁻¹.

FIG. 29 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 at varied LHSV and HMFconcentration. HMF=0.5-1%, P=150 psig air, T=120° C., LHSV=7.5-4.5 h⁻¹,GHSV=300 h⁻¹.

FIG. 30 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 at varied temperature.P=150 psig air, T=140-160° C., 0.5% HMF LHSV=7.5 h⁻¹, GHSV=300 h⁻¹.

FIG. 31 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 at varied LHSV atvaried temperature and at varied psi air. P=150-300 psig air, T=100-160°C., 0.5% HMF LHSV=7.5-15 h⁻¹, GHSV=300 h⁻¹.

FIG. 32 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28. P=150 psig air, T=140°C., 0.5% HMF LHSV=7.5 h⁻¹, GHSV=300 h⁻¹.

FIG. 33 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 and the condition ofFIG. 32 with the exception of decreased GHSV (GHSV=150 h⁻¹).

FIG. 34 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 and the condition ofFIG. 32 with the exception that P=500 psig air.

FIG. 35 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 and the condition ofFIG. 32 with the exception that GHSV=150 h⁻¹ and P=150 psig O₂.

FIG. 36 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 after Na₂CO₃ wash; 0.5%HMF, P=150 psig air, T=100° C., LHSV=7.5 h⁻¹, GHSV=300 h⁻¹.

FIG. 37 shows the concentration in weight % versus time on stream of theindicated starting material, products and by-products utilizing thecatalyst of FIG. 28 after a carbonate wash. 0.5% HMF, P=150 psig air,T=100° C., LHSV=7.5 h⁻¹, GHSV=300 h⁻¹.

FIG. 38 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 at varied temperaturein the presence of either air or O₂. 1% HMF in 40% HOAc, 150 psigair/O₂, T=100-140° C., LHSV=7.5 h⁻¹, GHSV=300 h⁻¹.

FIG. 39 shows HMF conversion and product selectivity as a function oftime on stream utilizing the catalyst of FIG. 28 in the presence ofeither air or O₂ at varied GHSV. 0.5% HMF in 40% HOAc, P=150 psigair/O₂, T=140° C., LHSV=7.5 h⁻¹, GHSV=150-300 h⁻¹.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

In general, the invention pertains to methods of oxidizing hydroxymethylfurfural (HMF) in an aqueous solution. The oxidation process can beperformed as a batch reaction or as a continuous flow process. Astarting material is provided comprising HMF in water. Depending on thedesired product, the mixture can be basic, neutral or acidic. Where anacidic aqueous solution solvent system is utilized, an appropriate acidcan be added such as, for example, acetic acid. Due to the relativelylow solubility of HMF oxidation products in neutral and acidic water,appropriate reactor designs can be utilized to accommodate solidsformation. Feeds having up to 10% HMF have been successfully used in abatch reactor, and higher HMF concentrations are feasible. In a packedbed up-flow reactor the HMF concentration can preferably be less than orequal to about 3% by weight. Under mildly basic conditions, such asthose created by providing Na₂CO₃ into the reaction mixture, productshaving carboxylic acid groups are present as the sodium salt and haveincreased solubilities. Solids formation and feed concentration aretypically not problematic under these conditions. The addition of astrong base, such as NaOH, can lead to undesirable side reactions suchas the Cannizzaro reaction.

The starting material comprising HMF is provided into a reactor and atleast one of air or O₂ is provided as oxidant. A pressure of fromatmospheric to the pressure rating of the equipment can be utilizeddepending upon the desired reaction rate. A preferred pressure cantypically be in the range of 150-500 psi. Similarly an appropriatereaction temperature can be from about 50° C. to about 200° C., with apreferred range of from 100° C. through about 160° C.

The starting material is contacted with a catalyst within the reactor.The catalyst typically comprises a metal on a support material.Preferably the metal comprises Pt. The support material can comprise,for example, C, ZrO₂, Al₂O₃, SiO₂, or TiO₂. The particular supportmaterial utilized can depend upon, for example, the desired oxidationproduct(s) (discussed below).

In particular instances, the reaction mixture can contain Na₂CO₃, orcomparable weak base. Where Na₂CO₃ is utilized, such can be present inthe mixture at a molar ratio of from 0.25 to 2.0 moles Na₂CO₃ to HMF,preferably at a molar ratio of from 0.5 to about 1.0 relative to HMF.The use of Na₂CO₃ or alternative carbonate bases is advantageousrelative to conventional methodology. Other relatively weak bases(relative to NaOH) are contemplated such as those weaker than NaOH andstronger than the furan carboxylate product such that the furancarboxylate (FDCA, FFCA) remains in the soluble salt form. Possiblealternative bases include metal carbonates, metal bicarbonates, metalphosphates, and metal hydrogen phosphates. These relatively weak basescan be present in the feed and do not need to be added slowly over thecourse of the reaction to prevent side reactions that tend to occur withstrong bases such as NaOH.

Where continuous reaction is utilized in an up-flow packed bed reactorwith a feed of about 1-3 wt % HMF, the liquid hourly space velocity(LHSV) can be, for example, from about 3 h⁻¹ to about 15 h⁻¹, and gashourly space velocity (GHSV) can be for example from about 75 h⁻¹ toabout 600 h⁻¹. These parameters can vary depending on the feedconcentration and the reactor design and are presented for referenceonly.

The oxidation of HMF to fully oxidized product FDCA can occur withinvolvement of partially oxidized species DFF, HMFCA, and FFCA via theroutes shown in the following diagram.

As shown in the accompanying figures and as discussed further below,particular catalysts and sets of reaction conditions and parameters canfavor selective production of one or more reaction products orintermediates. For example, under particular reaction conditions, HMFconversions of 100% were achieved with selectivity to FDCA as high as98% relative to all other reaction products, intermediates andbyproducts.

Studies utilizing various catalysts including those described herein forneutral and acidic feed solutions indicate that catalysts such as thosedescribed having high metal loading on low surface area (conditions thattypically gives low dispersion of metal) produce the highest HMFconversion and FDCA selectivity. These results run counter toconventional wisdom that generally indicates best catalytic performanceutilizing catalysts having high dispersion and high surface area.

Inorganic support materials can also be preferred for the presentcatalysts. Catalysts supported on carbon can result in product holdupand inhibition. Holdup can also increase generally with surface areaeven for those inorganic support materials, which tend to sorb less thancarbon supports.

As indicated above, the fully oxidized product FDCA is relativelyinsoluble in water. Higher solubility can be attained in carboxylic acidsolvent such as, for example, acetic acid/water mixtures. Table 1 showsthe solubility of FDCA in various acetic acid/water mixtures. Asindicated, the solubility in a 40/60 ratio HOAc/H₂O is about twice thesolubility in pure water. The oxidation of 0.5 weight % HMF in 40/60HOAc/H₂O with 150 psi O₂ over a 5% Pt/ZrO₂ catalyst at 140° C. achieves100% HMF conversion with up to about 80% selectivity to FDCA.

TABLE 1 Solubility of FDCA in acetic acid/water mixtures wt % wt % Vol %HOAc Vol % H₂O 70° C. 25° C. 0 100 0.327 0.086 40 60 0.779 0.153 50 500.746 0.173 60 40 0.596 0.171 70 30 0.592 0.143 90 10 0.458 0.138 100 00.193 0.080

As illustrated in FIGS. 1-11, HMF oxidation reactions performedutilizing 5% Pt supported on granular carbon can be utilized toselectively produce FFCA relative to individual alternativeintermediates and oxidation products. In particular instances, suchreactions under appropriate conditions can selectively produce FFCArelative to all other oxidation products, intermediates and byproducts.

Referring to FIGS. 12-13 studies were performed utilizing a 5% Pt/SiO₂catalyst. Under appropriate reaction conditions the 5% Pt/SiO₂ catalystcan be utilized to selectively produce DFF relative to individualalternative oxidation products, intermediates and byproducts. Inparticular instances, DFF can be produced selectively relative to allother oxidation products, intermediates and by products (see FIG. 12).In the presence of Na₂CO₃, the 5% Pt/SiO₂ catalyst can be utilized toselectively produce FFCA as its Na salt (see FIG. 13).

The results of studies utilizing an alternative Pt/C catalyst arepresented in FIGS. 14-17. As shown, an appropriate Pt/C catalyst can beutilized under the indicated reaction parameters to selectively produceFDCA relative to all other oxidation products, intermediates andbyproducts.

Studies were performed utilizing a 5% Pt supported on Al₂O₃ catalyst,the results of which are presented in FIGS. 18-27. The 5% Pt supportedon Al₂O₃ can be utilized to selectively produce FDCA and FFCA relativeto alternative oxidation products and byproducts. Under alternativeconditions the Pt/Al₂O₃ catalyst can also be utilized to selectivelyproduce FDCA relative to all other oxidation products, intermediates andbyproducts.

A 5% Pt supported on ZrO₂ catalyst was also utilized to perform HMFoxidation studies. The results of these studies are presented in FIGS.28-39. The data indicates that the 5% Pt supported on ZrO₂ can produce100% HMF conversion with selective production of FDCA relative to allother oxidation products intermediates and byproducts. Utilizing thesame catalyst, an adjustment of reaction conditions can be utilized toproduce, selectively, a product mixture of FDCA and FFCA.

Product isolation, separation and purification can be achieved basedupon solubility differences between the compounds (HMF, individualintermediates, byproducts and FDCA) in aqueous and organic solvents.

In another aspect, the invention pertains to preparation of DFF fromHMF. A mixture is provided containing HMF in an organic solvent. Themixture is contacted with the catalyst containing active γ-MnO₂ and issubjected to reflux temperature for a time of from about 6 hours toabout 12 hours. The organic solvent can preferably be a chlorinatedsolvent such as methylene chloride. MnO₂ is removed by filtrationfollowed by solvent removal. The resulting solids are dissolved in hotwater and DFF is precipitated. HMF conversion is approximately 80% withDFF product selectivity nearly 100%. This methodology is advantageousrelative to conventional methodology which utilizes MnO₂ to oxidizefurandimethanol (FDM) as the starting material, where the yield ofproduct DFF is reported as only 40%.

In yet another aspect the invention pertains to a method of producing anoxidation catalyst. Extrudated ZrO₂ is provided and the extrudated ZrO₂is calcined. The calcined ZrO₂ is crushed and sieved and is subsequentlymixed with platinum(II) acetylacetonate to form a mixture. The mixtureis subjected to rotary evaporation to form a product which issubsequently calcined. The product is activated by reducing underhydrogen and passivated under a flow of 2% O₂.

Example 1 Oxidation of HMF to FDCA in a Fixed-Bed Continuous FlowReactor

A ⅜-inch stainless-steel thick-walled tube (0.065 inch wall thickness)was utilized as a tubular reactor. 4 mL (4.7254 g) of dry 5% Pt/ZrO₂catalyst was placed in the reaction tube with 60-80 mesh glass beads atthe inlet and outlet of the catalyst bed. The reactor tube was attachedto a liquid-gas feed system and placed within a tube furnace. Thecatalyst was wetted with deionized water and reduced prior to testing at150 psi pressure and ambient temperature with a hydrogen flow. After 30minutes the hydrogen was shut off and the system was vented and purgedwith nitrogen.

Airflow of approximately 100 mL/min was established until the systempressure increased to 150 psig. Water was introduced at a flow rate of0.5 mL/min with a high-pressure liquid pump and the airflow was thendecreased to a flow rate of 20 mL/min (GHSV=300 h⁻¹). The temperatureoperating set point of the system was increased to 100° C. Uponachieving 100° C. a 0.5 weight % feed solution of HMF was fed into thecatalyst bed at a rate of 0.2 mL/min (LHSV=3 h⁻¹). At 40-60 minutereaction time intervals (measured from the time feed was initiated)liquid samples of the product exiting the reactor were collected forliquid chromatography analysis. Liquid chromatography results for eachsample taken showed 100% conversion of HMF with selectivity to FDCAattaining 98% within 40 minutes under these conditions. Conversion andselectivity remained constant for another 220 minutes of testing.

Example 2 Oxidation of HMF in a Batch Reactor

Batch oxidation of HMF was conducted in a 40 mL autoclave with a glassliner. 0.50 grams of 5% Pt on ZrO₂, 10 mL of deionized water and amagnetic stir bar were added into the glass liner. The vial and contentswere sealed in the autoclave and were purged with nitrogen. The contentswere then activated by reducing with hydrogen at room temperature. After10 minutes the hydrogen was purged from the reactor with nitrogen. Thenitrogen line was subsequently removed and no attempt was made toexclude air.

An oxygen line was attached to the reactor and the reactor was filledwith oxygen. 0.51 grams of HMF in 5 mL of water was added to theautoclave with a syringe through a valve placed at the top of theautoclave cap. A magnetic stir plate was turned on and the reactor waspressurized to 150 psi with oxygen. The autoclave was heated to 100° C.After 6 hours reaction time a sample was removed from the reactor bycooling to 40° C., venting the oxygen to atmospheric pressure andwithdrawing the sample through the top valve using a syringe and an 18gauge needle. The sample was analyzed utilizing liquid chromatographyand indicated that 80% of original HMF had reacted with approximately68% conversion to DFF and 32% conversion to FFCA. The autoclave wascharged to 150 psi with oxygen and was again heated to 100° C. for anadditional 17 hours. The reactor was then cooled and vented and anothersample removed. After a total of 23 hours reaction the HMF wascompletely depleted. Liquid chromatography revealed an absence ofdetectable DFF and FFCA. The primary product revealed utilizing liquidchromatography analysis was FDCA indicating complete oxidation of HMF.The only other product detected was levulinic acid, which resulted fromthe hydrolysis of HMF.

Example 3 Preparation of DFF from HMF

1.155 grams of HMF was dissolved in 50 mL of methylene chloride. 7.0606grams of activated MnO₂ was added to the solution and the mixture washeated to reflux for 8 hours. The MnO₂ was removed from the reactionmixture by filtration and the solids were washed with additionalsolvent. The solvent was removed to produce and off-white solid. Liquidchromatography analysis of the solid indicated 80% DFF and 20%un-reacted HMF. A trace amount of FDCA was observed utilizing UVdetection. The solid was dissolved in hot water and was subsequentlycooled to precipitate DFF having a 98.5% purity. Selectivity of theoxidation reaction to DFF was substantially 100%.

Example 4 Preparation of 5% Pt on a ZrO₂ Support

Extrudated ZrO₂ received from Engelhard was calcined at 700° C. for 2hours. The calcined ZrO₂ was crushed and sieved to 40-80 mesh size.10.6318 grams of the crushed ZrO₂ was mixed at room temperature with0.7593 grams of platinum(II) acetylacetonate in 50 mL flask. The flaskwas then mounted on a rotary evaporator and evacuated by a vacuum pumpto reach 10 mmHg. The flask was rotated at 60 rpm for 10 minutes. Aftera thorough mixing the flask was heated to about 180° C. utilizing a heatgun. During the process the color of the catalyst changed from a lightbrown color to black. The temperature was then increased to about 240°C. Heating was stopped after approximately 20 minutes. The catalyst wasthen calcined in air for about 3 hours at 350° C. with a temperatureramp rate of 5° C. per minute.

Activation was carried out by reducing the catalyst in a fixed-bedreactor at 330° C. for 3 hours. The hydrogen flow rate was 40 mL/min.After reduction the reactor was cooled to room temperature underhydrogen and was then purged with helium for 30 minutes. Passivation wasconducted by flowing 2% O₂ into the reactor at 40 mL/min overnight. Thecatalyst was unloaded from the reactor and was transferred to a storagecontainer until use.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A method of oxidizing hydroxymethyl furfural (HMF), comprising:providing a starting material comprising HMF in a solvent comprisingwater into a reactor; providing at least one of air and O₂ into thereactor; and contacting the starting material with a catalyst comprisingPt, on a support material, the contacting being conducted at a reactortemperature of from about 50° C. to about 200° C., wherein the methodselectively produces diformyl furan relative to all other products,intermediates and byproducts.
 2. The method of claim 1 wherein thesolvent comprises acetic acid.
 3. The method of claim 5 wherein theacetic acid is present at a ratio of 40:60 relative to water.
 4. Themethod of claim 1 wherein the support material comprises at least one ofZrO₂, Al₂O₃, SiO₂, TiO₂ and carbon.
 5. The method of claim 1 wherein thecatalyst comprises 5% Pt on a SiO₂ support material.